Williams destroyed Caroline Wozniacki 6-0, 6-3. During the match , Williams amazed spectators with and off-balance left-handed forehand.
“I haven’t practiced it in a couple of months,” Williams said. “I wish I could have hit it better.”
Serena completed her day by pairing with sister Venus downing No. 2-seeded Sara Errani and Roberta Vinci of Italy, 6-1, 6-1 to move into the doubles semifinals.
Azarenka topped Angelique Kerber 6-4, 7-5.
The other singles semifinal will have a pair of Russians facing off. Sharpova knocked out Kim Clijsters 6-2, 7-5, while Kirilenko upset No. 6 Petra Kvitova 7-6(3), 6-3.
“I’m really happy that one of us will have a chance to go for gold,” said Sharapova of her Russian teammate, opponent and friend.